C

RSA Hash Binary Data and Sign (and Verify)

See more RSA Examples

Demonstrates how to sign the hash of binary data. Also demonstrates how to verify the RSA signature. C

#include <C_CkPrivateKey.h>
#include <C_CkRsa.h>
#include <C_CkBinData.h>
#include <C_CkPublicKey.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkPrivateKey privKey;
    HCkRsa rsa;
    const char *originalData;
    HCkBinData bdData;
    HCkBinData bdSignature;
    HCkPublicKey pubKey;
    HCkRsa rsa2;
    BOOL bVerified;

    success = FALSE;

    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    // Load an RSA private key for signing.
    privKey = CkPrivateKey_Create();
    success = CkPrivateKey_LoadEncryptedPemFile(privKey,"qa_data/pem/rsa_passwd.pem","passwd");
    if (success == FALSE) {
        printf("%s\n",CkPrivateKey_lastErrorText(privKey));
        CkPrivateKey_Dispose(privKey);
        return;
    }

    rsa = CkRsa_Create();
    CkRsa_UsePrivateKey(rsa,privKey);

    // We have some binary data (in hex) to sign
    originalData = "0102030405060708090A";
    bdData = CkBinData_Create();
    CkBinData_AppendEncoded(bdData,originalData,"hex");

    // Hash (SHA-256) and sign the hash:
    bdSignature = CkBinData_Create();
    success = CkRsa_SignBd(rsa,bdData,"sha256",bdSignature);
    if (success == FALSE) {
        printf("%s\n",CkRsa_lastErrorText(rsa));
        CkPrivateKey_Dispose(privKey);
        CkRsa_Dispose(rsa);
        CkBinData_Dispose(bdData);
        CkBinData_Dispose(bdSignature);
        return;
    }

    // Show the RSA signature in base64
    printf("%s\n",CkBinData_getEncoded(bdSignature,"base64"));

    // ------------------------------------------
    // Get the public key from the private key
    pubKey = CkPublicKey_Create();
    CkPrivateKey_ToPublicKey(privKey,pubKey);

    // Verify the signature..
    rsa2 = CkRsa_Create();
    CkRsa_UsePublicKey(rsa2,pubKey);

    bVerified = CkRsa_VerifyBd(rsa2,bdData,"sha256",bdSignature);
    printf("signature verified: %d\n",bVerified);


    CkPrivateKey_Dispose(privKey);
    CkRsa_Dispose(rsa);
    CkBinData_Dispose(bdData);
    CkBinData_Dispose(bdSignature);
    CkPublicKey_Dispose(pubKey);
    CkRsa_Dispose(rsa2);

    }